1. Field of the Invention
This invention relates to a radiation detecting cassette having a solid state radiation detector accommodated within a casing.
2. Description of the Related Art
In the field of radiography for medical diagnosis and the like, various solid-state radiation detectors (whose main part comprises semiconductors; hereinafter also simply referred to as “detectors”) which detect radiation penetrating a subject and produce an image signal carrying radiographic image information of the subject (see, for example, U.S. Pat. No. 6,268,614 and Japanese Unexamined Patent Publication No. 2000-284056 have recently been proposed and brought into practical use. Concomitantly with this, various radiation detecting cassettes having a case accommodating therein such a solid-state radiation detector and the like (see, for example, U.S. Patent Laid-Open No. 20020014594 and Japanese Unexamined Patent Publication No. 2002-014170 have been proposed.
Such a radiation detecting cassette is relatively thin and made in portable size. This allows radio photographing with a very high degree of freedom. For example, even for a patient who is not ambulatory, a radio photograph can be taken by placing the radiation detecting cassette under a body part of the patient to be radio photographed while keeping the patient on a bed, and then moving a radiation source of a radiation image information recording apparatus to a position on a side of the patient opposite the radiation detecting cassette.
As one specific example, the radiation detecting cassette may have a construction where the solid-state radiation detector and an electric circuit board for processing a signal detected by the detector are secured inside a casing of the cassette, and where the solid-state radiation detector and the electric circuit board are connected with each other via a flexible circuit board.
In order to prevent damage to the solid-state radiation detector accommodated within such a radiation detecting cassette when the cassette is subjected to outside impact, aforementioned Japanese Unexamined Patent Publication No. 2002-014170 proposes a radiation detecting cassette, in which a shock absorbing material is disposed on an upper side (i.e., a side to be exposed to the radiation) of the solid-state radiation detector, while a lower side of the solid-state radiation detector is secured to the frame. With this configuration, the solid-state radiation detector cannot move towards the bottom of the radiation detecting cassette. Therefore, if the solid-state radiation detector is subjected to a shock in the direction towards the bottom thereof, shock cannot be absorbed.
On the other hand, when elastomeric bodies such as rubber or gel are used to sandwich the solid-state radiation detector therebetween for supporting the upper and lower surfaces of the detector as proposed in U.S. Patent Laid-Open No. 20020014594 mentioned above, it is difficult to ensure the positional precision of the solid-state radiation detector within the casing because the elastic bodies tend to change their shape.